It is known to integrate a switch in the end cap that is screwed onto the flashlight casing, the battery (batteries) or the storage batteries being inserted into the flashlight casing with the end cap unscrewed. With flashlights of this type one contact of the switch is connected to a spiral spring that on the one hand fixes the batteries inside the flashlight and on the other hand forms a connection with one pole of the battery, so that the current flows via the spiral spring. In order to create a closed electric circuit in the switched-off state, usually the other contact is positioned by the end cap so that the electric current flows from there further via the thread or other electrical connections over the flashlight casing to the light source.
The disadvantage of circuits in conventional flashlights is on the one hand that the current is guided through a plurality of connections such that a specific contact resistance is effective at each connection. Furthermore, due to the current flow inside the spiral current a self-induction voltage is induced that counteracts the actual current flow. Both of these lead to a lower voltage being available for the light source, so light output of the light source is markedly reduced.